Using python to manipulate vertices
You can do this by iterating through all of the objects in the scene which are found at bpy.data.objects. This is all the objects in all the all the scenes. You could also use bpy.contex.scene.objects which would be the objects in the current scene. Then you would want to make sure it was a mesh object by checking its type. Then get all the vertex positions, convert them to world space, and make them tuples, if you want. In the end you get this:

import bpy
for object in bpy.data.objects:
    if object.type == "MESH": #check if mesh object
        verts = [object.matrix_world * vert.co for vert in object.data.vertices] #get vertex data
        tup_verts = [vert.to_tuple() for vert in verts] #convert to tuples
        print(tup_verts) #display list


You could add tup_verts to a larger list if you wanted, and you can leave the positions as Vectors by accessing verts instead of tup_verts

In more recent versions of blender (>=2.80) it is necessary to use the "@" operator for the element-wise matrix multiplication instead of "*". I.e. "object.matrix_world @ vert.co". See this answer: https://blender.stackexchange.com/a/129474/22220